This invention relates to digital loop carder transmission systems.
In digital loop carder transmission systems, such as Subscriber Loop Carder (SLC.RTM.) Systems, bidirectional communication usually takes place between a local digital switch and a remote terminal located in the vicinity of a customer's premises. Information is transferred over the bidirectional link in time slots which are positioned in a particular frame format. This frame format will differ depending on the type of interface at the local digital switch. One type of framing, designated "Fs" or D-4 mode, utilizes a sequence of 12 frames to form a superframe and supervisory signaling bits embedded in a certain pattern. This frame format is used with the standard TR8 interface. A standard TR303 interface at the local digital switch requires a superframe of the "Fe" type or extended superframe (ESF) which comprises a sequence of 24 frames in a superframe with supervisory signaling embedded in a different pattern.
While newer equipment is built for compatibility with the TR303 interface, it is also desirable to permit a remote terminal to process information in a way which is compatible with existing TR8 interfaces.